The goal of this project is to study the pharmacologic activity and the biochemical mode of action of new antitumor agents of the pyrimidine nucleoside class. Present studies are focused on 5-azacytidine and 5,6-dihydro-5-azacytidine, a reduced analog of the latter with greater chemical stability than the parent compound. BIBLIOGRAPHIC REFERENCES: Voytek, P., Beisler, J.A., Abbasi, M.M., and Wolpert-DeFilippes, M.K.: Comparative studies of the cytostatic action and metabolism of 5-azacytidine and 5,6-dihydro-5-azacytidine. Cancer Research, 37:1956-1961, 1977. Futterman, B., Derr, C.J., Beisler, J.A., Abbasi, M.M. and Voytek, P.: Studies on the cytostatic action, phosphorylation and deamination of 5-azacytidine and 5,6-dihydro-5-azacytidine in HeLa cells. Biochemical Pharmacology, 1977 (in press).